Where do you get rails?

I was also unable to find rails for this chassis, but I had a spare set of Supermicro MCP-290-00053-0N rails which fit acceptably well. I had to buy new screws to mount the rails on the case, though. They appear to be item 38041-A from Midwest fasteners, but any brand of 4mm x 6mm .70 12 machine screw should work.